uniq

Official Description

Removes or lists repeated lines in a file.

Syntax

uniq [-cdu] [-f fields] [-s chars] [input-file [output-file]]

Options

-c displays the count of occurrences of the line.

-d displays repeated lines only.

-f fields ignores specified fields when comparing lines.

-s chars ignores the specified number of chars when doing comparisons.

-u displays unique lines only.

Oddities

Repeated lines must be on consecutive lines to be found.

You can arrange them with the sort command before processing.

Example

$ uniq utest
den
cheryl
cheryl cheryl den
mark                         # Mark shows up once
den
den cheryl
dencheryl
den cheryl
$
$ uniq -c utest
   1 den
   1 cheryl
   1 cheryl cheryl den
   3
					mark # There were four lines of mark 1 den 1 den cheryl 1 dencheryl ...

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